1. Field of the Invention
The present invention relates to a valve fastening structure of a reciprocating compressor, and more particularly, to a valve fastening structure of a reciprocating compressor for fixing a suction valve to a piston using a magnet.
2. Description of the Background Art
In general, the suction valve of a compressor, which is arranged in the suction side of a compression space, is opened and shut according to a pressure difference during the suction and compression motions of a piston, and thus restricts the degree of suction of fluid. FIG. 1 is a vertical sectional view showing an example of a reciprocating compressor, in which such a suction valve is loaded.
As shown in FIG. 1, a conventional reciprocating compressor includes a ring-shaped frame 1 installed inside a casing V, whose bottom is filled with oil, a cover 2 fixedly installed on one side of the frame 1, a cylinder 3 fixed to the center of the frame 1 in a horizontal direction, an inner stator assembly 4A fixed to the outer circumference of the frame 1 that supports the cylinder 3, an outer stator assembly 4B fixed to the outer circumference of the inner stator assembly 4A with a predetermined slit between the inner stator assembly 4A and the outer stator assembly 4B, a magnet assembly 5, which is interposed in the slit between the inner stator assembly 4A and the outer stator assembly 4B and forms the moving magnet of a driving motor (not shown), a piston 6, which is integrally fixed to the magnet assembly 5, the piston 6 for sucking up/compressing refrigerant gas, while being in a sliding motion inside the cylinder 3, an inner resonance spring 7A and an outer resonance spring 7B for inducing the magnet assembly 5 to be continuously in a resonant motion in the slit between the inner stator assembly 4A and the outer stator assembly 4B, and a discharge valve assembly 8, which is loaded in the leading end of the cylinder 3, the discharge valve assembly 8 for restricting the discharge of compression gas during the reciprocating motion of the piston 6.
As shown in FIGS. 2A and 2B, in the piston 6, a head 6b is formed in the front part of a body 6a of a predetermined length. A connector 6c connected to the magnet assembly 5 is formed in the hind part of the body 6a. A refrigerant channel F for guiding the refrigerant gas to the cylinder 3 is formed in the body 6a and the head 6b. A suction valve 9 for restricting the suction of the refrigerant gas through the refrigerant channel F is fastened and fixed to the front part of the head 6b of the piston 6 by a fixing bolt B. Reference numerals 6d, 9a, 9b, DP, SP, and O respectively denote a gas opening, a switching portion, valve fastening through hole, a discharge pipe, a suction pipe, and an oil feeder.
The conventional reciprocating compressor operates as follows.
When current is applied to the inner and outer stator assemblies 4A and 4B to thus let the magnet assembly 5 be in a linear reciprocating motion, the piston 6 combined with the magnet assembly 5 is in the linear reciprocating motion inside the cylinder 3, thus causing a pressure difference in the cylinder 3. The refrigerant gas in the casing V is sucked up into the cylinder 3 through the refrigerant channel F of the piston 6 due to the pressure difference in the cylinder 3 and is compressed and discharged. Such a series of processes are repeated.
At this time, when the piston 6 moves toward the hind part and sucks up the refrigerant gas, the refrigerant gas pushes aside the suction valve 9, while passing through the refrigerant channel F and the gas opening 6d. Therefore, the suction valve 9 does not drift away due to the reciprocating motion of the piston 6 to thus maintain the realiability of the compressor when the suction valve 9 is firmly loaded in the piston 6.
This is why a method of fastening the suction valve 9 to the leading end of the head 6b of the piston 6 using the additional fixing bolt B is disclosed in a conventional technology, as shown in FIGS. 2A and 2B.
However, in such a conventional suction valve combining apparatus, since the head of the fixing bolt B protrudes into the compression space of the cylinder 3, a dead volume is created to thus deteriorate compression efficiency. Also, it is difficult to sense the positions of the top dead center and the bottom dead center of the piston 6 due to the head of the protruding fixing bolt B. Accordingly, it is difficult to control stroke with respect to the reciprocating motion of the piston 6.
In the suction valve fixing structure of the reciprocating compressor, as shown in FIGS. 3A and 3B, the suction valve 9 is directly loaded in the leading end of the piston 6 by welding in order to minimize the dead volume and to easily control the stroke of the piston. Reference numeral W denotes a welding point.
However, when the suction valve 9 is combined with the leading end of the piston 6 by welding, poor welding may be caused since the piston 6 is formed of cast iron in consideration of castability and the suction valve 9 is formed of high-carbon spring steel. Accordingly, the reliability of the compressor deteriorates.
Therefore, an object of the present invention is to provide a valve fastening structure of a reciprocating compressor, which is capable of minimizing a dead volume between a cylinder and a piston, easily controlling the stroke of the piston, and firmly fixing a suction valve to the piston.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a valve fastening structure of a reciprocating compressor, comprising a piston, which is combined with a moving magnet of a driving motor and is in a linear reciprocating motion inside a cylinder and in which a refrigerant channel is formed in the direction of the reciprocating motion, a suction valve arranged in the leading end of the piston, the suction valve for opening and shutting the refrigerant channel of the piston, and magnets inserted into and fixed to the leading end of the piston, the magnets for fixing the suction valve by magnetic force.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.